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Diffstat (limited to 'src/hash.c')
| -rw-r--r-- | src/hash.c | 190 |
1 files changed, 190 insertions, 0 deletions
diff --git a/src/hash.c b/src/hash.c new file mode 100644 index 0000000..5c92e94 --- /dev/null +++ b/src/hash.c @@ -0,0 +1,190 @@ +/* + * Hash function implementation + * + * See mailing list thread on "Consistent hashing alternative to sdbm" + * http://marc.info/?l=haproxy&m=138213693909219 + * + * Copyright 2000-2010 Willy Tarreau <w@1wt.eu> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + * + */ + + +#include <haproxy/compiler.h> +#include <haproxy/hash.h> + + +unsigned int hash_wt6(const void *input, int len) +{ + const unsigned char *key = input; + unsigned h0 = 0xa53c965aUL; + unsigned h1 = 0x5ca6953aUL; + unsigned step0 = 6; + unsigned step1 = 18; + + for (; len > 0; len--) { + unsigned int t; + + t = *key; + key++; + + h0 = ~(h0 ^ t); + h1 = ~(h1 + t); + + t = (h1 << step0) | (h1 >> (32-step0)); + h1 = (h0 << step1) | (h0 >> (32-step1)); + h0 = t; + + t = ((h0 >> 16) ^ h1) & 0xffff; + step0 = t & 0x1F; + step1 = t >> 11; + } + return h0 ^ h1; +} + +unsigned int hash_djb2(const void *input, int len) +{ + const unsigned char *key = input; + unsigned int hash = 5381; + + /* the hash unrolled eight times */ + for (; len >= 8; len -= 8) { + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + hash = ((hash << 5) + hash) + *key++; + } + switch (len) { + case 7: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 6: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 5: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 4: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 3: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 2: hash = ((hash << 5) + hash) + *key++; __fallthrough; + case 1: hash = ((hash << 5) + hash) + *key++; break; + default: /* case 0: */ break; + } + return hash; +} + +unsigned int hash_sdbm(const void *input, int len) +{ + const unsigned char *key = input; + unsigned int hash = 0; + int c; + + while (len--) { + c = *key++; + hash = c + (hash << 6) + (hash << 16) - hash; + } + + return hash; +} + +/* Small yet efficient CRC32 calculation loosely inspired from crc32b found + * here : http://www.hackersdelight.org/hdcodetxt/crc.c.txt + * The magic value represents the polynom with one bit per exponent. Much + * faster table-based versions exist but are pointless for our usage here, + * this hash already sustains gigabit speed which is far faster than what + * we'd ever need. Better preserve the CPU's cache instead. + */ +unsigned int hash_crc32(const void *input, int len) +{ + const unsigned char *key = input; + unsigned int hash; + int bit; + + hash = ~0; + while (len--) { + hash ^= *key++; + for (bit = 0; bit < 8; bit++) + hash = (hash >> 1) ^ ((hash & 1) ? 0xedb88320 : 0); + } + return ~hash; +} + +/* CRC32c poly 0x11EDC6F41 (RFC4960, Appendix B [8].) */ +static const uint32_t crctable[256] = { + 0x00000000L, 0xF26B8303L, 0xE13B70F7L, 0x1350F3F4L, + 0xC79A971FL, 0x35F1141CL, 0x26A1E7E8L, 0xD4CA64EBL, + 0x8AD958CFL, 0x78B2DBCCL, 0x6BE22838L, 0x9989AB3BL, + 0x4D43CFD0L, 0xBF284CD3L, 0xAC78BF27L, 0x5E133C24L, + 0x105EC76FL, 0xE235446CL, 0xF165B798L, 0x030E349BL, + 0xD7C45070L, 0x25AFD373L, 0x36FF2087L, 0xC494A384L, + 0x9A879FA0L, 0x68EC1CA3L, 0x7BBCEF57L, 0x89D76C54L, + 0x5D1D08BFL, 0xAF768BBCL, 0xBC267848L, 0x4E4DFB4BL, + 0x20BD8EDEL, 0xD2D60DDDL, 0xC186FE29L, 0x33ED7D2AL, + 0xE72719C1L, 0x154C9AC2L, 0x061C6936L, 0xF477EA35L, + 0xAA64D611L, 0x580F5512L, 0x4B5FA6E6L, 0xB93425E5L, + 0x6DFE410EL, 0x9F95C20DL, 0x8CC531F9L, 0x7EAEB2FAL, + 0x30E349B1L, 0xC288CAB2L, 0xD1D83946L, 0x23B3BA45L, + 0xF779DEAEL, 0x05125DADL, 0x1642AE59L, 0xE4292D5AL, + 0xBA3A117EL, 0x4851927DL, 0x5B016189L, 0xA96AE28AL, + 0x7DA08661L, 0x8FCB0562L, 0x9C9BF696L, 0x6EF07595L, + 0x417B1DBCL, 0xB3109EBFL, 0xA0406D4BL, 0x522BEE48L, + 0x86E18AA3L, 0x748A09A0L, 0x67DAFA54L, 0x95B17957L, + 0xCBA24573L, 0x39C9C670L, 0x2A993584L, 0xD8F2B687L, + 0x0C38D26CL, 0xFE53516FL, 0xED03A29BL, 0x1F682198L, + 0x5125DAD3L, 0xA34E59D0L, 0xB01EAA24L, 0x42752927L, + 0x96BF4DCCL, 0x64D4CECFL, 0x77843D3BL, 0x85EFBE38L, + 0xDBFC821CL, 0x2997011FL, 0x3AC7F2EBL, 0xC8AC71E8L, + 0x1C661503L, 0xEE0D9600L, 0xFD5D65F4L, 0x0F36E6F7L, + 0x61C69362L, 0x93AD1061L, 0x80FDE395L, 0x72966096L, + 0xA65C047DL, 0x5437877EL, 0x4767748AL, 0xB50CF789L, + 0xEB1FCBADL, 0x197448AEL, 0x0A24BB5AL, 0xF84F3859L, + 0x2C855CB2L, 0xDEEEDFB1L, 0xCDBE2C45L, 0x3FD5AF46L, + 0x7198540DL, 0x83F3D70EL, 0x90A324FAL, 0x62C8A7F9L, + 0xB602C312L, 0x44694011L, 0x5739B3E5L, 0xA55230E6L, + 0xFB410CC2L, 0x092A8FC1L, 0x1A7A7C35L, 0xE811FF36L, + 0x3CDB9BDDL, 0xCEB018DEL, 0xDDE0EB2AL, 0x2F8B6829L, + 0x82F63B78L, 0x709DB87BL, 0x63CD4B8FL, 0x91A6C88CL, + 0x456CAC67L, 0xB7072F64L, 0xA457DC90L, 0x563C5F93L, + 0x082F63B7L, 0xFA44E0B4L, 0xE9141340L, 0x1B7F9043L, + 0xCFB5F4A8L, 0x3DDE77ABL, 0x2E8E845FL, 0xDCE5075CL, + 0x92A8FC17L, 0x60C37F14L, 0x73938CE0L, 0x81F80FE3L, + 0x55326B08L, 0xA759E80BL, 0xB4091BFFL, 0x466298FCL, + 0x1871A4D8L, 0xEA1A27DBL, 0xF94AD42FL, 0x0B21572CL, + 0xDFEB33C7L, 0x2D80B0C4L, 0x3ED04330L, 0xCCBBC033L, + 0xA24BB5A6L, 0x502036A5L, 0x4370C551L, 0xB11B4652L, + 0x65D122B9L, 0x97BAA1BAL, 0x84EA524EL, 0x7681D14DL, + 0x2892ED69L, 0xDAF96E6AL, 0xC9A99D9EL, 0x3BC21E9DL, + 0xEF087A76L, 0x1D63F975L, 0x0E330A81L, 0xFC588982L, + 0xB21572C9L, 0x407EF1CAL, 0x532E023EL, 0xA145813DL, + 0x758FE5D6L, 0x87E466D5L, 0x94B49521L, 0x66DF1622L, + 0x38CC2A06L, 0xCAA7A905L, 0xD9F75AF1L, 0x2B9CD9F2L, + 0xFF56BD19L, 0x0D3D3E1AL, 0x1E6DCDEEL, 0xEC064EEDL, + 0xC38D26C4L, 0x31E6A5C7L, 0x22B65633L, 0xD0DDD530L, + 0x0417B1DBL, 0xF67C32D8L, 0xE52CC12CL, 0x1747422FL, + 0x49547E0BL, 0xBB3FFD08L, 0xA86F0EFCL, 0x5A048DFFL, + 0x8ECEE914L, 0x7CA56A17L, 0x6FF599E3L, 0x9D9E1AE0L, + 0xD3D3E1ABL, 0x21B862A8L, 0x32E8915CL, 0xC083125FL, + 0x144976B4L, 0xE622F5B7L, 0xF5720643L, 0x07198540L, + 0x590AB964L, 0xAB613A67L, 0xB831C993L, 0x4A5A4A90L, + 0x9E902E7BL, 0x6CFBAD78L, 0x7FAB5E8CL, 0x8DC0DD8FL, + 0xE330A81AL, 0x115B2B19L, 0x020BD8EDL, 0xF0605BEEL, + 0x24AA3F05L, 0xD6C1BC06L, 0xC5914FF2L, 0x37FACCF1L, + 0x69E9F0D5L, 0x9B8273D6L, 0x88D28022L, 0x7AB90321L, + 0xAE7367CAL, 0x5C18E4C9L, 0x4F48173DL, 0xBD23943EL, + 0xF36E6F75L, 0x0105EC76L, 0x12551F82L, 0xE03E9C81L, + 0x34F4F86AL, 0xC69F7B69L, 0xD5CF889DL, 0x27A40B9EL, + 0x79B737BAL, 0x8BDCB4B9L, 0x988C474DL, 0x6AE7C44EL, + 0xBE2DA0A5L, 0x4C4623A6L, 0x5F16D052L, 0xAD7D5351L +}; + +uint32_t hash_crc32c(const void *input, int len) +{ + const unsigned char *buf = input; + uint32_t crc = 0xffffffff; + while (len-- > 0) { + crc = (crc >> 8) ^ crctable[(crc ^ (*buf++)) & 0xff]; + } + return (crc ^ 0xffffffff); +} |